Erosion

1. Erosion CHAPTER 3

2. Wearing Down Earth’s Surface is worn down through Weathering. Chemical Weathering Mechanical Weathering

3. Moving Earth Weathered particles (sediment) is moved from one place to another through Erosion. Agents include: Wind Water Ice Gravity

4. Building up… Deposition- when the agents (wind, water, Ice, and gravity) lay down the sediment it was carrying. Heavier pieces of sediment settle to the earth before the lighter ones.

5. Gravity - Mass movement Gravity is the force that moves rock and other materials downhill. Mass movement Landslides Mudslides Slump Creep

6. Landslide When Gravity pulls Rock and Soil down a slope. Caused by: Earthquakes Road Construction Occur very quickly and are very dangerous.

8. Mudslide Occur after heavy rains and Gravity pulls water soaked soil particles down a slope Contain up to 60% water Also called mudflow Can happen very quickly and are very dangerous

10. Slump Happens when a mass of earth is pulled down a slope by gravity. Earth moves all at once, not in particles. Water soaks into clay layer at bottom of slope and reduces friction and the slump occurs Can happen quickly.

11. Slump

12. Creep When the earth on a slope is Slowly pulled down by gravity. Main cause is freezing and thawing Can cause objects on the surface to tilt at weird angles. The most continuous of the mass movements.

13. Creep

14. WATER EROSION Erosion by Moving Water Moving water is the major agent of the erosion that has shaped Earth’s land surface.

15. Energy of moving water When gravity pulls water downhill it begins to move. The Energy of movement is called Kinetic Energy. The moving river has Kinetic Energy. The more kinetic energy that a river has, the more eroding power it has.

16. How sediment gets into rivers “Most sediment washes or falls into the river as a result of mass movement or runoff.” Runoff is the excess water from rainfall that does not absorb into soil.

17. Factors that effect Water Erosion Slope The greater the slope, the faster the water moves, the greater the eroding power. Allows river to carry more load (sediment in the river) Volume of flow The more water moving through the river, the faster it moves, the greater the eroding power. Increases the load of the river. Stream bed shape The less stream bed in contact with the river, the faster it moves, the greater the eroding power. Turbulence is caused by obstacles in the river. They slow down the current but can increase eroding power. Ex: Rapids in the river.

18. Erosion by rivers Through erosion, a river creates valleys, waterfalls, flood plains, meanders and oxbow lakes.

19. Meander When the slope of a river decreases the speed of the river decreases and the river begins to create bends. Then bends continually change over time.

20. meandering

21. Waterfall River flows over areas with different types of rock. River erodes softer rock underneath a layer of hard rock. This continues until waterfall is created.

22. V-Shaped Valley When a river flows through mountains, a valley forms.

23. Oxbow lake When a meander gets cut off from a river.

24. Flood Plain Area near a river that collects water when the river overflows. Contains silt that increases the soils fertility.

26. Deposition by rivers Deposition creates landforms such as alluvial fans and deltas.

27. Alluvial Fan Created when a river comes out of a mountain, slows down and drops its sediment.

28. Delta When a river meets up with a large body of water the river slows and drops its sediment.

29. Glaciers (Ice) Formation: 1. Form when snowfall consistently exceeds snowmelt for a long period of time.

30. How they Erode They scrape away (abrasion), and collect rock (plucking) when it moves across the landscape. This creates scrapes (striations) in the rock. They bulldoze earth out of the way. They carve into the earth and leave sediment (till). Sometimes in mounds called a moraine

31. Where in Connecticut Long Island Sound was created by Glacial movements.

32. How it formed

33. Glaciers Types Valley – A glacier that forms in between mountains. Continental- a glacier that forms mostly on a continent. Page 92-93 Know the features created by glaciers.

34. How Waves form Waves form when the energy in the wind is transferred to the water. Makes water particles move up and down. Up and down energy moves forward to create wave. Wave grows taller as it nears the shore

35. Erosion by Waves Waves erode the landscape by: Impact – Wave hitting rocks with great force Abrasion- small rock particles carried by the wave wear away rock.

36. Landforms by Wave Erosion and deposition Longshore drift (deposition) Beaches (deposition) Spit (deposition) Sea Caves Wave cut cliffs Sea Arch Headland

37. Longshore Drift As waves crash into the shore at angles, they pick up sediment and deposit it farther down the shoreline.

38. Longshore Drift

39. Beaches When waves deposit sediment along the coastline.

40. Spit A result of Longshore drift in which a landform results that looks like a finger like projection. Example: Cape Cod

41. Spit

42. Sea Cave When waves impact a cliff on the shoreline it wears away the softer rock to create a cave.

43. Sea Cave

44. Wave Cut Cliff When a sea cave is eroded really badly, the rock above it will collapse to create a very steep cliff side at the waters edge.

45. Wave Cut Cliff

46. Sea Arch When wave action erode layers of soft rock leaving behind an arch shape formation made of harder rock.

47. Sea Arch

48. Sea Stack A result of a Sea Arch that collapses due to the weight of the area directly over the arch.

49. Sea Stack

50. Waterfall http://www.school-portal.co.uk/GroupDownloadFile.asp?file=21604 Oxbow lake http://www.school-portal.co.uk/GroupDownloadFile.asp?file=21606 Wave erosion http://www.school-portal.co.uk/GroupDownloadFile.asp?file=21400

51. Wind Erosion Wind Erosion takes place in areas where there is little grouncover to protect the soil. Examples: Deserts, Beaches, overplowed farmland.

52. How it works Deflation Wind picks up particles of soil in different ways and transports it to other areas. Small claylike are moved really easily Medium size particles bounce along the surface Large particles (boulders) roll along the surface.

53. Example of Deflation

54. Dust Bowl and Deflation Due to human and natural causes, the soil became dry and loose. Overplowing, drought. Wind gusts came on consistent basis and deflated the soil by taking it away with it. Millions of acres of farmland was wasted.

55. Wind Landforms by Erosion Hoo Doo When wind transporting soil particles physically weathers soft rock layers and leaves a pillar of the harder rock.

56. Blowouts When deflation carves out a depression in the land as it carries sediment away from an area.

57. Blowout pic

58. Desert pavement When wind carries away layers of soil and leaves behind the large rocks that were to heavy to be moved by the wind.

60. Deposition by Wind Wind carries sediment which then gets deposited in other places Examples include: sand dunes and Loess Deposits

61. Sand Dune When wind blown sand is deposited around an object (cactus, rock, plants at the beach, etc) and builds up into a large pile.

62. Loess Deposits When the fine clay particles of wind erosion are deposited far away from original source.